The present invention relates to a rivet and method for riveting metal members together for assembling automotive vehicle structures.
It is known that the manufacture of automotive vehicles often requires that metal members be attached to each other to form automotive vehicle structures. Pierce riveting is one potential method of attaching such members, particularly, metal sheets. Pierce riveting typically requires a sharpened end portion of a rivet to pierce through a first of two stacked metal sheets, and through at least a portion of a second of the stacked sheets. During such piercing, the sharpened end portion of the rivet is typically deformed or bent to secure the rivet to the sheets. For conventional pierce riveting processes, however, large amounts of force may be required to pierce the sheets. Moreover, such processes typically rely solely on a mechanical interlock of the rivet to secure the sheets together and may not secure the sheets together with a desired amount of strength. Therefore, there is a need for improved pierce riveting techniques, apparatuses or both, for achieving high integrity attachment of metal members such as metal sheets.
The present invention meets these needs by providing an improved method of riveting a first metal member to a second metal member, with particular utility in the formation of components for an automotive vehicle. The method involves riveting the members by providing a piercing rivet having a central axis, a generally disk-shaped head portion and an annular portion extending outwardly from a bottom surface of the head portion. The annular portion defines a cavity and a plurality of passages extend through the annular portion. An adhesive in a flowable state is disposed in the cavity of the annular portion. For riveting, a first metal member is stacked on a second metal member, wherein each of the members has a first side and a second side, and at least a portion of the second side of the first member is in overlapping contact with at least a portion of the first side of the second member for forming an overlapped region. The first and second metal members are placed between a rivet assembly and a die, the rivet assembly including a punch, the die having a cavity. Thereafter, the rivet is driven through the first metal member and partially through the second metal member in the overlapped region. During driving, the annular portion of the rivet is deformed radially outward away from the central axis of the rivet to interferingly secure the rivet to the members thereby attaching the members to each other. The adhesive is forced out of the cavity through the plurality of passages of the rivet thereby positioning the adhesive between an outer annular surface of the rivet and portions of the first member and the second member. Thereafter, the adhesive is cured to adhesively secure the rivet to the first and second members.
The present invention also provides a rivet for riveting a first metal member to a second metal member. The rivet includes a generally disk-shaped head portion disposed about a central axis and having a substantially flat top surface and a generally conical bottom surface. The rivet also has an annular portion centered about the central axis and extending outwardly from a bottom surface of the head portion. The annular portion includes an outer annular surface and a sharpened piercing edge. The annular portion also includes an inner annular surface at least partially defining a substantially cylindrical cavity within the annular portion. A plurality of passages are radially disposed in the annular portion and extend from the inner surface to the outer surface. Moreover, the rivet is adapted to receive an adhesive in a flowable state in the cavity of the annular portion such that the adhesive may be forced through the plurality of passages to adhesively secure to the outer annular surface of the rivet and to the first and second members.
The present invention thus provides an improved rivet and riveting technique for providing securing piercing rivets in stacked members thereby more securely fastening the members together. The ability to combine the mechanical interlock of a rivet with the additional fastening strength of an adhesive creates particularly high integrity joints for securing stacked members together.